Tokyo Electric Power Co. detected the highest radiation levels found so far near tanks holding contaminated water used to cool reactors at its wrecked Fukushima Dai-Ichi plant, the company said.
Readings of 2,200 millisieverts per hour were found yesterday in an area where levels of 1,800 millisieverts had been detected on Aug. 31, Mayumi Yoshida, a spokeswoman for the utility known as Tepco, said today by phone. The increase could be due to a slight difference in where where the measurement was taken, she said.
“It fluctuates when you move a little bit,” so the higher reading doesn’t necessarily indicate rising radioactivity levels, Yoshida said.
Yesterday’s hourly reading is equivalent to the amount of radiation that 44 plant workers may be exposed to in a full year under government guidelines.
The reading was at one of four radiation hot-spots near storage tanks reported by Tepco over the weekend, one of which led crews to a leaking pipe that was repaired on Sept. 1. Investigators will now deploy more advanced sensors to locate the source of yesterday’s reading, Yoshida said.
Tepco reported a 300-ton leak last month from a tank used to store contaminated water in what the country’s nuclear regulator designated the worst accident since the March 2011 earthquake and tsunami caused reactors to meltdown.
Tepco has subsequently boosted the number of tank-inspection patrols from twice to four times a day and increased its inspection staff to 60 members from 10, it said.